Medicine has a “Goldilocks” problem. Many therapies are safe and effective only when administered at just the right time and in very precise doses – when given too early or too late, in too large or too small an amount, medicines can be ineffective or even harmful. But in many situations, doctors have no way of knowing when or how much to dispense.

Now, a team of bioengineers led by UC San Francisco’s Hana El-Samad, PhD, and the University of Washington’s David Baker, PhD, have devised a remarkable solution to this problem – “smart” cells that behave like tiny autonomous robots which, in the future, may be used to detect damage and disease, and deliver help at just the right time and in just the right amount.